I regularly freeze yolks and whites. For yolks in particular, I'd suggest freezing them in 8-ounce units. Whisk them together to break down the membrane that surrounds them. Spread them out into ice cube trays. 1 cube tray equals about 1 ounce of egg yolk. 1 EY = .66 of an ounce. Therefore, each cube compartment = 1 2/3 egg yolks. When grossing up, go for the high side.